Level Switches

About Level Switches and Level Switch Manufacturers Including: Chambered Level Switch, Displacer Level Switch, Float Level Switch, Liquid Level Switch & Mechanical Level Switch.

Level switches are meant to monitor the amount of liquid or bulk material contained in various sizes of vessels like storage tanks, feeder chutes, stirrers, sluices, etc. Level switches can also operate as flow control devices or liquid interface indicators. They can be mounted on vessels or suspended inside of them. Level switch size varies depending on the type and amount of its mechanisms and the size of the vessel in which it is operating. A level switch, especially the common float switch, can look a lot like a “bobber.” Level switch manufacturers might design their products to have multiple actuation points — each actuation point looking like a “bob” with a length of thinner connector in between the points.

Stainless steel, brass and plastic are common materials level switch manufacturers utilize to construct their product lines of chambered level switches, displacer level switches, float level switches, liquid level switches, mechanical level switches and more. The construction of a level switch is dependent upon what temperature, pressure and type of liquid or material will make up its environment. Stainless steel is ideal for harsh environments such as high temperatures and pressures and corrosive conditions. Stainless steel level switches are commonly used in food processing, medical, and heating and cooling equipment.

Polypropylene and polysulfone, available in different colors, are good choices for acidic conditions, such as in electroplating and metal cleaning, for lower-temperature food processing applications and for general-purpose applications in commercial or consumer appliances and equipment. Brass works in petroleum-based liquids, such as lubricating oils, gasoline and diesel fuels, and is used in storage tanks of vehicles, generators, and transmission and hydraulic systems, and in lubrication, recovery, refining and fuel processing equipment. Level switch manufacturers can also cater to specific applications, many offering customization.

Level switches can be made to operate with very simple to quite complex sensor designs. Simple designs might include magnetic features and be triggered by pressure, temperature or buoyancy. For example, a level switch can be attached to a plastic tube enabling it to sense the air pressure change as the liquid rises around and within the tube. Other level switch devices include thermal sensors, vibrating sensors and optical sensors, which can be modified to recognize specific substances or to reveal when a certain viscosity, density, opacity or thermal conductivity condition is reached. Other level switch types include electromechanical and hydrostatic level switches, ultrasonic level switches, capacitive and conductive level switches, microwave level switches, and optical and radiometric level switches.

Level Switches and Level Switch Manufacturers Images Provided by SOR Inc.

Types of Level Switches

• Capacitive or conductive level switches are able to channel or collect a charge of electricity.
  
• Chambered level switch designs include encasings, or chambers, that surround the sensor or switch mechanisms. Chambers can be flanged or sealed to offer protection or hermetic air-tightness.
  
• Displacer level switch devices are affected by buoyancy force changes on a weight (displacer) heavier than the liquid. Through a spring mechanism, the suspended weight is attached to an attraction sleeve that moves into or out of a magnet field, thus actuating or deactuating the switch.
  
• Electric level switches contain open or closed contacts that indicate the presence or absence of liquid.
  
• Electromechanical level switches work with a combination of electric and mechanical parts.
  
• Float level switch mechanisms can most simply be a rod floating in a liquid that is raised until a pump, an indicator, an alarm or other device is activated. It could also be a mercury switch enclosed in a hinged float, a suspended “bobber” attached to an attraction sleeve that actuates a magnet field or a more complex sensor construction.
  
• Hydrostatic level switches are sensitive to the static, or stationary, water pressure acting on them.
  
• Liquid level switch constructions monitor the amount of fluid in a vessel. Ultra-low liquid level switches are available to detect very low levels for early indication of a liquid presence and effective use of expensive liquids.
  
• Mechanical level switch designs offer versatility and rugged, industrial constructions relying on buoyancy principles and made of floats or displacers, spring mechanisms, attraction sleeves, optional chambers and magnet fields that activate switching mechanisms.
  
• Microwave level switches are made up of two separate parts, a transmitter and a receiver. The transmitter emits a burst of energy at approximately 200 times a second toward the receiver; a substance interruption of the microwave between the two devices is the trigger.
  
• Multi-point switches can be engineered to provide a number of actuation points.
  
• Optical level switches are cost-effective, compact, quickly installable options that contain no moving parts but use LEDs, which transmit infrared light, prisms and photo transistors. When a translucent liquid meets the point where the light contacts the prism, the light is reflected into the water and does not allow the photo transistor to energize.
  
• Pneumatic level switches are air-pressure activated through valves and amplifiers.
  
• Thermal level switches include temperature sensors that provide activation when a heat change occurs as the liquid surrounds them. Some can sense the difference between the temperatures of the air space and the liquid.
  
• Two-stage level switch devices are designed with a flood-preventing capability. If liquid reaches the second stage, the switch will turn the pump off and/or sound an alarm.
  
• Ultrasonic level switches utilize high-frequency (above the audible level) pulse wave technology.
  
• Vibrating level switches can come with reed, probe or tuning fork sensors, which all have similar constructions of a driver coil that vibrates a paddle. The switch detects a dampening of the vibration when the sensor is surrounded by a substance.

Terms Related to Level Switches

Aperture – The space between contiguous parallel wires, expressed in millimeters.
 
Buoyancy – An object’s upward force produced by the fluid in which it is fully or partially submerged.

Mercury Switch – A sealed glass tube containing a minimal amount of liquid mercury and two unconnected electrodes that produce electricity flow when the tube is moved past a certain angle so that the liquid metal pools in between the electrodes, making a complete circuit. Once back in the original position, the current stops instantly.

Opacity – Difficulty to see through.

Polypropylene or polypropene (PP) – A thermoplastic polymer that is rugged and unusually resistant to many chemical solvents, bases and acids.

Polysulfone or PSU – A polymer thermoplastic material that offers toughness, rigidity, high-strength and transparency, while also maintaining its characteristics between negative 100 °C and positive 150 °C.

Sluice – A water channel with a gate used to regulate levels and flow rates in rivers, canals and wastewater treatment plants, and to retrieve minerals during the mining process.

Viscosity – The thickness of a liquid, or its resistance to flow.